Centrifugal pump



May 23, 194 H. HORNSCHUCH CENTRIFUGAL PUMP Filed March 20, 1942 3Sheets-Sheet 1 INVENTOR JYarmdlioonJc/auc/a HI 5 ATTORNEY.

y 3 1944- H. HORNSCHUCH 2,349 73l CENTRIFUGAL PUMP Filed March 20; 19423 Sheets-Sheet 2 INVENTOR mnmiflmm/schucfb BY v H l5 ATTORNEY.

Patented May 23, 1944 'UNiTED STATE s PATENT OFFICE cnn'rairuou. rim

Hanna Hornschuch, Easton, Pa.', .assignor Ingersoll-Rand Company, NewYork, N. Y.,' a corporation of New Jersey Application March 20, 1942,Serial No. 435,444

' '-6 Claims. (Cl. 10

without necessitating the operation of the pump at reduced speeds.Another object is to assure the delivery of liquid to a pump impeller ina state best suited to assure maximum impelling effect upon the liquid.

Otherobjects will be in part obvious part pointed out hereinafter.

In the drawings accompanying this specifica-' tion and in which similarreference numerals refer to similar parts,

Figure 1 is an elevation, partly in section, of a centrifugal pumpconstructed in accordance with the practice of the invention,

Figure 2 is a view similar to Figure 1, although somewhat enlarged,showing the impelling element of the pump in section,

Figures- 3 and 4 are perspective views of the pumplmpellers, and

Figures 5 and 6 are views similar to Figure 2 showing modified forms ofthe invention.

Referring to the drawings and at first more particularly to Figures 1 to4 inclusive, 20 designatesa centrifugal pump comprising a' c sing 2!having an impeller chamber 22 and an 1 et passage 23 for conveyingliquid to the impeller chamber. The casing-also has an outlet passage 24forthe discharge of liquid from the impeller chamber, and a head 25 issecured to the casin and in 21 by bolts 26 to form a closure for oneend' ofthe impeller chamber 22.

The head 25 is provided than the sleeve 3! to receive packing material3| which is disposed about the sleeve 3! for prevent ing leakage ofliquid through the bore 21 exteriorlyof the sleeve. The inner end of thepacking material 33 seats against an annular wearing piece 35 insertedin the bore 21. The imwith a horizontal bore 21 to receive; amongtotherelements, a-shaft 23 that extends through the hub 23 of animpeller 33peller 33 and which may be termed the main impeller issecured to theshaft 28 by clamping its hub against the sleeve 3| with a nut 38 on theouter extremity of the reducedportion 32 of the shaft.-

In order to avoid subjecting the packing members 33 and 34 to the highpressure of the liquid in the impeller chamber 22 the impeller isprovided on its end surface with radially extending vanes 31 to ejectliquid from the space between the impeller and the head 'andtherebymaintains a zone of low pressure adjacent the end of the bore 21.

In accordance with the practice of the invention, the liquid pumped bythe impeller is delivered thereto by a second or booster impeller 38also arranged in the impeller chamber 22. The booster impeller 33 iscapable of free rotation relatively-to the main impeller and is mounted,for such rotation, upon-an end portion 39 of theshaft 23, the shafthaving a sleeve 33 to provide a bearing surface for bushings llextending into the opposite ends of thehub 32 of the impeller 33. I

A seat. in the form of a washer 43, clamped against a shoulder 34 at thejuncture of the reduced and end portions 32 and 33, respectively,

of the shaft is provided for the inner end of the sleeve 40. A cap nut35 threaded upon the extremity of the end portion 33 of the shaftsecures the sleeve 30 and the washer-l3 in assembled positions andoverlies the'end of the outermost bushing ll to serve as an abutmenttherefor. The sleeve '40 is of such length and the cap nut and thewasher 33 are, in consequence, so spaced'with'respect to each other thatthe impeller 331s capable of rotating freely upon the shaftwithouthindrance from the elements restraining it from. endwisemovement.

In the form of the invention illustrated, the eye 36 of the impeller 30is of frusto-conical shape and itsbottom' 31 is defined by the innerwall43 of the impeller 30. Owing to this arrangement the inner ends 49 ofthe vanes 53. of the impeller 33 lie at an'acute angle with respect othe axis of the shaft and the inner end portions of the water-ways inthe impeller are only slightly curved as indicated at 5| so that therewill be only a'small degree of deviation of the course of the'liquidwithin the impeller 30. The vanes 53 may be of any known design toassure desired impelling surfaces but are preferably curved as indicatedmore particularly in Figure 4 of the drawings. v

.It is in the booster impeller 33 that the initial 1 peller balancingfunction. An outlet is provided transition from axial flow to radialflow of the liquid takes place. The vanes 52 of said impeller are, asindicated more particularly in Figure 3 of the drawing, of the curvedtype. They extend into the radial plane of the eye of the main impeller,and operate to deliver the liquid to the main impeller in a whirlingbody. As a preferred arrangement the inner or discharge ends 53 of thevanes 52 are separated by a suitable space 54 from the ends 49 of thevanes 50 of the main impeller in order to assure a full supply of liquidto the main impeller in all relative positions of the impellers.

The force serving to cause rotation of the booster impeller 38 isderived from the impeller 38. To this end the main impeller is providedon the end surface confronting the booster im' peller with a pluralityof radially extending ribs 55 for imparting rotary motion to the liquidin the adjacent portion of the impeller chamber 22,. The force thusgenerated acts against the side of a flange 55 on'the periphery of. theimpeller 38 and lying closely adjacent the ribs 55. The side of theflange 58 confronting the ribs 55 may, as shown, also be provided withradially extending ribs 51 to assure the utmost utilization of theforceor thrust of the rotating body of liquid] between the impeller 38and the flange 56.

The liquid serving the function of transmitting driving force from theimpeller 38 to the impeller 38 is cast centrifugally into the impellerchamber by the ribs 55 which cause a constant circulation of liquidbetween the impeller and the flange 55. Such liquid, in the presentinstance, is derived in part from the space 54 which communicates withthespace between the impeller 38 and the flange 55 through an. annulargroove 58 in the inner end of the rim 59 of the impeller38. The groove58 is of considerable depth to accommodate an annular flange 60 on theimpeller 38, and ample clearances exist between the annular surfaces ofthe groove 58 and the flange 58 so that liquid will flow freely throughthe groove. 7

Suitable balancing means are provided to assure against 'undue endthrust of the booster im- 38 in the direction of the inlet passage 23.To this end the booster impeller is provided with a cylindricalextension 5| on the endof the rim 59. The extension 5| extends rotatablyinto an annular groove 52 in the inner surface of a linerj3 defining theinlet passage directly adjathe bottom of the groove 82 to act againstthe end of the cylindrical extension for performing its for liquid fromthe groove 52 by passages 54 in the extension 8| and the rim 59 andleading into the groove 58. Thus, some of the liquid impelled by theribs for driving the booster impeller 38 is also derived from theimpeller chamber 22.

The operation of the device is as follows: At the beginning of rotationof the main impeller 38 the force generated by the ribs 55 may beinsufllcient to overcome the resistance of the booster impeller. Butupon acceleration of the impeller 38 this force will increase until itreaches a critical value sufllcient to setthe impeller 38 in motion. Asthe speed of the impeller 30 increases the it attains the maximum speedconsistent with the force serving to drive it.

Owing to the slippage that must naturally result between the driving anddriven elements the impeller 38 will, of course, operate at a somewhatlower speed than the main impeller. The extent of this differential inspeed will var in accordance with variations in size of the area on thebooster impeller against which the force is applied for driving it, aswill be readilyunderstood. 1

During this operation of the pump the liquid flowing through the inletpassage 23 will first be handled by the comparatively slow movingimpeller 38 so that a whirling motion will be imparted to .it fordelivering it as a whirling body to the main impeller which will impressadditional velocity to the liquid.

In practice, it has been found that, owing to the use of the boosterimpeller arranged and driven in the manner hereinbefore described, a

centrifugal pump of a given design may operate with increased emciencyat a considerably greater suction lift or at lower positive suction headand without necessitating reduced rotative speed of the impeller thanwould be the case if the liquid were pumped only by the main impeller.It has further been found that these advantages may be obtained withoutnecessitating an appreciable expenditure of additional power for drivingthe pump.

The modified form of the invention shown in Figure 5 differs from thatpreviously described principally in that the impellers are mounted uponseparate shafts arranged coaxiallywith respect to each other. Theimpeller 30 is avccdrdingly mounted upon the end of the shaft 28 whichhas threaded thereon a nut 35 for clamping the impeller upon the shaft.The impeller 38 is secured, in like manner, by a nut 85 upon a reducedend portion of a shaft 61.

The impeller 38 is suitably keyed to the shaft 61 and said shaft extendsthrough a packing element 58 in the end of the casing 2| and into abearing cage 69 exteriorly of the casing 2|. Suitable anti-frictionbearings 10 are arranged in the ends of the cage 59 for the shaft 8! andthe shaft preferably has shoulders H to abut the inner races of theanti-friction bearings for pre- The inlet passage 23 is, moreover,located within impeller 39 will alsoaccelerate until the head 12 and theinner end of the head forms a bounding surface for the impeller chamber22. In this form of the invention the main impeller designated 13 isopen on one side and a.

flange 14 on the periphery of the booster impeller 38 serves as a shroudfor the open. side of the main impeller. The flange I4 is disposedclosely adjacent the open side'of the impeller 13 so that its innersurface 15 will besubjected to frictional contact with the liquid in themain impeller and moving rotatively therewith for driving the boosterimpeller 38.

The booster impeller 38 is shown as being mounted rotatively upon an endportion 16 of the shaft 11 carrying the main impeller, and a collar 18on the shaft 11 lies between the hubs of the impellers to clamp theimpeller I3 against the sleeve 3| and to act as an abutmentfior theinnermost of the bushings 4| in ,the booster impeller.

I claim:

1. A centrifugal pump, ,comprising a casing to absorb power from thefluid pumped by the main impeller for effecting rotation of the saidsecond impeller.

2. A centrifugal pump, comprising a casing having an impeller chamber,an impeller in the impeller chamber, a shaft in the casing for theimpeller, means for locking the impeller to the shaft, and a secondimpeller supported by and freely rotatable upon the said shaft todeliver liquid to the first mentioned. impeller fluid-impelling means onthe side of the main impeller, and flange means on thesecond saidimpeller and having means on a side thereof presenting radiallyextending surfaces to absorb power from the fluid pumped by the saidfluid-impelllng means for effecting rotation of said'second impeller.

3. A centrifugal pump, comprising a casing having an impeller chamber, amain impeller in the impeller chamber, a second impeller for deliveringliquid to the main impeller, blade means on an outer side surface of themain impeller for imparting rotary motion to liquid in the impellerchamber, and blade means on the second impeller subjected to the forceof the liquid rotatlng in the impeller chamber for driving the secondimpeller.

4. A centrifugal pump, comprising a. casing having an impeller chamber,a main impeller in the impeller chamber, ribs on the side of the mainimpeller to impart a whirling motion to liquid in the impeller chamber,a second impeller in the said impeller chamber to deliver liquid to themain impeller, and a flange on the second impeller arranged adjacent thesaid ribs and having ribs subjected to the whirling motion of the liquidimpelled by the first-mentioned ribs for rotating the second impeller.

5. A centrifugal pump, comprising a casing having an impeller chamber,an open-type impeller in the impeller chamber, a second impeller todeliver liquid to the first mentioned impeller, and means on the secondimpeller forming a shroud for the open side of the open-type impeller.

6. A centrifugal pump, comprising a. casing having an impeller chamber,an open-type impeller in the impeller chamber, a second impellertoideliver liquid to the flrst mentioned impeller, and a flange on thesecond impeller forming a shroud for the open-type impeller and beingsubjected to the liquid passing through the open-type impeller fordriving said second impeller.

HANNS HORNSCHUCH.

